Method and apparatus for manufacturing multi-layered electro-optic devices

ABSTRACT

A method is provided for producing a hybrid multi-junction photovoltaic device. The method begins by providing a plurality of planar photovoltaic semi-transparent modules. Each of the modules is a fully functional, thin-film, photovoltaic device and includes first and second conductive layers and at least first and second semiconductor layers disposed between the conductive layers. The first and second semiconductor layers define a junction at an interface therebetween. The method continues by disposing the modules one on top of another and hybridly adhering them to each other. At least one of the modules is configured to convert a first spectral portion of optical energy into an electrical voltage and transmit a second spectral portion of optical energy to another of the junctions that is configured to convert at least part of the second spectral portion of optical energy into an electrical voltage.

STATEMENT OF RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No. ______(Attorney Docket No. 2800/2), filed on even date herewith, entitled“Multi-Layered Electro-Optic Devices”, which is incorporated byreference in its entirety herein.

BACKGROUND OF THE INVENTION

1. Field

The present invention relates generally to a method and apparatus formanufacturing electro-optic devices and more particularly to a methodand apparatus for manufacturing electro-optic devices that have multiplelayers and which can be produced by laminating or otherwise integratingtwo or more discrete electro-optic units or modules.

2. Related Art

Photovoltaic devices represent one of the major sources ofenvironmentally clean and renewable energy. They are frequently used toconvert optical energy into electrical energy. Typically, a photovoltaicdevice is made of one semiconducting material with p-doped and n-dopedregions. The conversion efficiency of solar power into electricity ofthis device is limited to a maximum of about 37%, since photon energy inexcess of the semiconductor's bandgap is wasted as heat. A photovoltaicdevice with multiple semiconductor layers of different bandgaps is moreefficient: an optimized two-bandgap photovoltaic device has the maximumsolar conversion efficiency of 50%, whereas a three-bandgap photovoltaicdevice has the maximum solar conversion efficiency of 56%. Realizedefficiencies are typically less than theoretical values in all cases.

Multi-layered or multi-junction devices are currently manufactured asmonolithic wafers, where each semiconductor layer is crystal-grown ontop of the previous one. As a result, the semiconductor layers areelectrically connected in series and have to be current-matched, inorder to obtain maximum conversion efficiency.

SUMMARY OF THE INVENTION

In accordance with the present invention, a method is provided forproducing a hybrid multi-junction photovoltaic device. The method beginsby providing a plurality of planar photovoltaic semi-transparentmodules. Each of the modules is a fully functional, thin-film,photovoltaic device and includes first and second conductive layers andat least first and second semiconductor layers disposed between theconductive layers. The first and second semiconductor layers define ajunction at an interface therebetween. The method continues by disposingthe modules one on top of another and hybridly adhering them to eachother. At least one of the modules is configured to convert a firstspectral portion of optical energy into an electrical voltage andtransmit a second spectral portion of optical energy to another of thejunctions that is configured to convert at least part of the secondspectral portion of optical energy into an electrical voltage.

In accordance with another aspect of the invention, the step of adheringis achieved by sequentially laminating each of the modules to another ofthe modules.

In accordance with another aspect of the invention, the disposing stepincludes laterally offsetting the modules from one another.

In accordance with another aspect of the invention, transparentinsulating layers are between the modules.

In accordance with another aspect of the invention, a part of theconducting layers of every module is exposed so that they are accessiblefor connection to external electrical circuits.

In accordance with another aspect of the invention, the step ofproviding the plurality of modules includes deposition of CIGS basedabsorber layers.

In accordance with another aspect of the invention, the step ofproviding the plurality of modules includes deposition of semiconductorabsorber layers with different bandgaps optimized for enhanced powerconversion efficiency.

In accordance with another aspect of the invention, a method is providedfor producing a hybrid electro-optic device. The method begins byproviding a plurality of planar electro-optic semi-transparent modules.Each of the modules is a fully functional, thin-film, electro-opticdevice and includes first and second conductive layers and at leastfirst and second semiconductor layers disposed between the conductivelayers. The first and second semiconductor layers define a junction atan interface therebetween. The method continues by disposing the modulesone on top of another, hybridly adhering them to each other and applyingan electrical contact to the conducting layers of each of the modules.

In accordance with another aspect of the invention, an apparatus isprovided for the hybrid manufacturing of a multi-layered electro-opticdevice. The apparatus includes a roll-to-roll system for feeding aplurality of electro-optic modules, at least one of which is disposed ona flexible substrate. Each of the modules is a fully functional,thin-film electro-optic device and includes first and second conductivelayers and at least first and second semiconductor layers disposedbetween the conductive layers. The first and second semiconductor layersdefine a junction at an interface therebetween. The apparatus alsoincludes an arrangement for monitoring and maintaining the speed,tension and temperature of the modules as they traverse the roll-to-rollsystem. At least one pressure roller is provided to exert a compressionforce for attaching two of the modules on top of each other in acontinuous fashion. An aligner system is also provided for positioningand laterally offsetting one of the modules over another of the modules.

In accordance with another aspect of the invention, each modulecomprises a plurality of segmented modules and the apparatus furtherincludes a view-vision system for selecting good known module segments,separating and detaching the module segments from a carrier film, andremoving remaining unused module segments.

In accordance with another aspect of the invention, An apparatus isprovided for the hybrid manufacturing of a multi-layered electro-opticdevice. The apparatus includes a pick and place system for handling aplurality of electro-optic modules, each one being a fully functional,thin-film electro-optic device. Each module includes first and secondconductive layers and at least first and second semiconductor layersdisposed between the conductive layers. The first and secondsemiconductor layers define a junction at an interface therebetween. Theapparatus also includes at least one pressure member to exert acompression force for attaching two of the modules on top of each otherin an automated fashion. An aligner system is provided for positioningand laterally offsetting one of the modules over another of the modules.

In accordance with another aspect of the invention, a process isprovided for manufacturing a hybrid electro-optic device. The methodincludes the step of feeding a plurality of electro-optic modulesthrough a roll-to-roll system. At least one of the modules has aflexible substrate. Each of the modules is a fully functional, thin-filmelectro-optic device that includes first and second conductive layersand at least first and second semiconductor layers disposed between theconductive layers. The first and second semiconductor layers define ajunction at an interface therebetween. The method continues bypositioning and laterally offsetting one of the modules over another ofthe modules and monitoring and maintaining the speed, tension andtemperature of the modules while they are being fed through theroll-to-roll system. A compression force is exerted for attaching two ofthe modules on top each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows operation of a multi-layered multi-junction photovoltaicthin film stack.

FIG. 2 is a laminated thin-film multi-junction photovoltaic deviceconsisting of three modules.

FIG. 3 is the cross-section of a single-junction photovoltaic module.

FIG. 4 shows examples of a photovoltaic module segmentation in onedimension (A) and two dimensions (B).

FIG. 5 shows a known method of solar cell encapsulation by lamination.

FIG. 6 shows the steps of laminating three separate photovoltaic modulesfollowed by encapsulation.

FIG. 7 is an apparatus and process for laminating one photovoltaicmodule having a flexible substrate on top of another photovoltaic modulehaving a rigid substrate using thermal and pressure laminationtechniques.

FIG. 8 is an apparatus and process for laminating one photovoltaicmodule having a flexible substrate on top of another photovoltaic modulehaving a rigid substrate using a sacrificial peal-off film substrate.

FIG. 9 is an apparatus and process for laminating multiple photovoltaicmodules having flexible substrates on top of another photovoltaic modulehaving a rigid substrate using thermal and pressure laminationtechniques.

FIG. 10 is a roll-to-roll apparatus and process for laminating onephotovoltaic module having a flexible substrate on top of anotherphotovoltaic module having a flexible substrate using extrusionlamination techniques.

FIG. 11 is an apparatus and process for laminating one segmentedphotovoltaic module having a flexible substrate on top of anothersegmented photovoltaic module having a rigid substrate using thermal andpressure lamination techniques.

FIG. 12 is an apparatus and process for laminating one segmentedpanel-size photovoltaic module on top of another segmented panel-sizephotovoltaic module having a rigid substrate using vacuum laminationtechniques.

DETAILED DESCRIPTION OF THE INVENTION Overview

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of exemplaryembodiments or other examples described herein. However, it will beunderstood that these embodiments and examples may be practiced withoutthe specific details. In other instances, well-known methods,procedures, components and circuits have not been described in detail,so as not to obscure the following description. Further, the embodimentsdisclosed are for exemplary purposes only and other embodiments may beemployed in lieu of, or in combination with, the embodiments disclosed.

Embodiments of this apparatus and method may facilitate the ability toefficiently and economically convert electromagnetic energy in the formof light into electrical energy in the form of electrical current.Embodiments of this apparatus and method may also facilitate largevolume production and widespread usage of photovoltaic devices.

The invention provides an alternative method of producing amulti-junction photovoltaic device. As well known in the art,multi-junction devices in general are one of the most efficient meansfor conversion solar energy into electricity. Currently, the bestperforming solar cells are based on epitaxially grown, crystallinesemiconductor multi-junctions. These are complex devices, which aremanufactured using difficult and expensive manufacturing processes andtheir high cost can make them prohibitive for wide spread use and highvolume production. This invention, on the other hand, proposes to usesubstantially less complex and expensive thin-film processing techniquesfor manufacturing of multijunction photovoltaic devices. Usingmulti-junction design and thin-film technology, a new efficientphotovoltaic device with expanded capabilities and application range canbe produced.

Thin-film materials, in general and depending on their chemical origin,can be deposited and layered by a variety of different methods, usingfor example evaporation, sputtering, spraying, inkjet printing etc.,most of which could be very inexpensive. Unlike crystalline,lattice-matched semiconductor films, any of these thin film materialscan be deposited on a variety of substrates and/or superstrates,including various glasses, polymers, metal sheets, foils and others.This further facilitates the production of efficient and inexpensivephotovoltaic media and enables a number of new manufacturing approaches,which are disclosed here.

As shown in FIGS. 1 and 2, a multi-layered and multi-junctionphotovoltaic device 100 may be produced from two or more photovoltaicmodules such as the three photovoltaic modules 111, 112 and 113 shown inFIGS. 1 and 2. Each of the photovoltaic modules 111, 112 and 113includes one or more junctions formed from an optically activesemiconductor having a specific bandgap. When photovoltaic device 100 isilluminated by light 101, one of its junction layers may absorb a partof light with photon energies above a corresponding bandgap and transmita part of light (i.e. light 102 and 103) with photon energies below acorresponding bandgap. The junctions within and between modules may bearranged so that the bandgaps of lower lying junctions are smaller thanthe bandgaps of higher lying junctions; this condition improves theconversion efficiency of the device. Furthermore, these modules may beelectrically isolated from each other and provided with two individualelectrical contacts 130 of opposite polarity for producing electricalcurrent connectors 140.

FIG. 3 shows an example of a single photovoltaic module 111, which maybe representative of the type of modules employed in the photovoltaicdevice 100 shown in FIGS. 1 and 2. In this example module 111 includesat least two semiconductor layers 303 and 304 that define a junction attheir interface 334. If more than two semiconductor layers are employed,the module 111 will include multiple junctions. The junction may be aheterojunction in which the layers 303 and 304 are formed of dissimilarmaterials. Alternatively, the junction or junctions may be of any typeknown in the art such as, but not limited to p-n junctions, p-i-njunctions, MIS junctions and the like. The module 111 may includeadditional semiconductor and buffer layers that alter or improve thedevice performance. Photovoltaic module 111 also includes transparentconducting layers 302 and 305, so that all of layers 302-305 aresituated in a monolithic stack on a substrate 301. In summary, a singlemodule (e.g. modules 111, 112 and 113) includes at least a substrate,two conducting layers, and two or more semiconductor layers (which form1 or more junctions). An individual module from time to time may bereferred to herein as a subcell.

As previously noted, the number of photovoltaic modules, N may be largerthan two: the greater the number of modules, the higher is the maximumachievable conversion efficiency. It should be noted that a photovoltaicdevice that is formed from N modules includes N or more junctions,depending on the number of semiconductor layers in each module. Thenumber of junctions in each module forming a single photovoltaic devicemay or may not be the same. Also, the semiconductor materials that areemployed in the modules may be, for example, a compound semiconductorformed from an inorganic, polymer-based material, an organic dye-basedmaterial, a nanoparticle composite material, a quantum dot compositematerial, or a mixture of the above materials. The specific materialcomposition used in each module will generally be optimized for theparticular photovoltaic device that is being designed. These modulesforming the photovoltaic device are situated in a stack and furtherprocessed so that they adhere to one another.

A number of electro-optic materials have been developed in recent yearsthat are suitable for thin film processing techniques, including CdTe,CIGS (Copper Indium Gallium Selenide), organic and polymersemiconductor. These thin-film technologies greatly simplify theproduction of a multi-junction, non-single crystalline (e.g.,polycrystalline, amorphous) photovoltaic device. Unlike wafer-basedsemiconductor technologies that use such materials as Si, Ge, GaAs andGaInP, thin-film technologies allow deposition of functionalsemiconductor thin films only few microns thick on a variety ofsubstrates including flexible substrates. Furthermore, it generallyenables the production of large area, single-sheet, multi-layeredelectro-optic devices, e.g. using roll-to-roll manufacturing. The latteris not possible using a standard single-crystal semiconductor technologydue to the typically limited and small size of semiconductor wafers. Asa general rule, thin film materials are typically direct bandgapsemiconductors, unlike some of the single crystal semiconductors, suchas Si and Ge.

Thin-film layers formed from various semiconductors may be manufacturedseparately as large sheets on independent substrates. These sheets thencould be attached, glued, laminated, or otherwise hybridly joined,together to form a single large area, integrated multi-junction device.Since multiple junction layers are hybridly integrated into a singlesheet, they can be produced and optimized independently from oneanother. All of the individual photovoltaic modules may be attached to acommon substrate that may be sturdy yet flexible. The substrate also maybe coated with a reflective layer. One or more surfaces in this devicecould be textured to provide a relief pattern for multiple lightreflections and scattering, which improves light absorption andsubsequently its power conversion efficiency.

A large number of different semiconductor materials are currentlyavailable and known to be suitable for thin-film manufacturing. Oneadvantage of this invention is that its approach is universal and doesnot rely on a particular material. Some examples of currently availablesemiconductors could be divided into two large groups: organic andinorganic semiconductors. Organic semiconductors include various typesof -conjugated polymers and oligomers. Although they are particularlysuitable for low-cost manufacturing and could be deposited by simpleevaporation, their photovoltaic performance is not yet as good as thatof inorganic semiconductors. Suitable inorganic materials include CdTe,CIGS, a-Si and the like. All these semiconductors tend to have a directbandgap and subsequently strong optical absorption at photon energiesabove the bandgap. Thus a rather thin film of only few microns thickcould absorb most photons and achieve very high quantum efficiency.

In the present invention individual modules may be first produced fromthe aforementioned materials using known thin film technologies. Themodules may be manufactured using transparent conducting layers andpreferably transparent substrates. Alternatively, an opaque sacrificialsubstrate may be used that subsequently could be detached and discardedor reused. After fabricating the individual modules they may beassembled in a single stack and hybridly attached to each otheraccording to the techniques discussed below.

This approach to fabrication of multijunction photovoltaic devices isvery flexible and can be tailored for a very large variety ofsemiconductor materials. However, there are some specific requirementswhich need to be met in most cases: (1) the conducting layers in theindividual modules should be substantially transparent to light withphoton energies below the bandgap of a corresponding semiconductorlayer; (2) the bandgaps of a semiconductor material in a light absorbinglayer of each junction module should satisfy the relation (in the orderfrom top to bottom):

E₁>E₂> . . . >E_(n)   (1)

where n is the number of junctions in the photovoltaic device; (3) mostof the materials used in the manufacturing of laminated multi-junctionsolar cell, including conducting, semiconducting and insulating layers,should be compatible with low temperature, low cost thin-filmmanufacturing methods and processes; (4) some of the individual modulesare preferably flexible to facilitate the lamination process; (5) mostof the exposed surfaces should be optically smooth (roughness is smallerthan the wavelength of light) in order to avoid excessive lightscattering.

In most cases there may be only a few exceptions to these requirements.For example, the bottommost conducting layer need not be transparent.Since there are no additional modules below it, this layer could beeither opaque or reflective, in the latter case increasing lightabsorption and subsequently its conversion efficiency. Also, conductinglayers may include partially transmitting metal grids for reducingin-series resistance of corresponding modules. Furthermore, at least oneof the modules could be manufactured using approaches other thanthin-film technology, as long as additional modules can be addedhybridly, e.g. via sequential lamination. Although, it is preferable touse substrates that are optically smooth on both sides, it may bepossible to reduce the effect of optical scattering on the roughsubstrate surfaces by adding intermediate refractive index-matchinglayers between modules. Such layers could also perform dual functions;as for example a thin adhesive layer may bond together two adjacentmodules and at the same time smooth out an optical interface betweenthese modules, so that optical scattering between them is reduced.

Hybrid integration of multiple modules on a single substrate enablesseveral intermediate, but critical testing procedures. Since all ofthese modules can be manufactured separately to produce fullyfunctioning photovoltaic cells, the resulting cells or modules, could betested and screened on performance before they are assembled into afully stacked multi-junction device. Thus only good known modules willbe used in the eventual assembly and attachment process. This proceduremakes a tremendous difference in the overall production yield,performance and cost of the multi-junction photovoltaic devices. Forexample, if three modules, each with a single junction, are hybridlyintegrated have a 50% yield each, then the overall manufacturing yieldof this integrated triple junction photovoltaic device will still be 50%(assuming nearly 100% yield in the process of assembling the subcells).On the other hand, a monolithically integrated device, in which the samethree junctions are grown or deposited sequentially on the samesubstrate, will have 12.5% manufacturing yield, due to the fact that onecannot pick and choose the good parts in this process and thus the totalyield is the product of all fractional yields for each junction layer.The difference in yield becomes even more dramatic if the individualmodules each contain more than one junction.

A plant for large volume manufacturing of thin-film solar cells wouldtypically use roll-to-roll or similar large area processing facility. Tofacilitate the selection process of good known parts for furtherintegration into photovoltaic devices, individual subcells could besegmented as shown in FIG. 4 for one-dimensional (A) and two-dimensionalsegmentation (B). All of the segments or subcells 401 in this instanceare nominally identical and manufactured simultaneously on the same rollof film, foil or substrate 402. These subcells, however, areelectrically and physically separated from each other, so that they canbe tested both optically and electrically and selected on the basis oftheir individual performance. Thus only the best performing sections ofa particular module could be separated, diced out, peeled off orotherwise detached from the rest of the substrate roll. Thus selectedsections could then be used in the hybrid assembly of multi-junctiondevices.

Lamination technology is currently used in solar cell manufacturingprimarily for encapsulation and protection from adverse environmentalconditions. Lamination is defined herein as a method of sandwiching twolayers, one of which may be a plastic or other flexible film, with theapplication of pressure and/or heat, usually with an adhesive layerbetween them. Both of these layers are pre-manufactured as standalonelayers. FIG. 5 shows prior art applications of laminates in solar cellmanufacturing, in which one or more coats of protective plastic 501 arelaminated above and/or underneath the module 111. They may also be usedto protect part of electrical leads 502. The protective laminated filmsare electrically inactive and play no direct role in the operation of aphotovoltaic device. On the other hand, in the present invention thelamination process is used to attach optically and electrically activelayers. In fact, each one of the laminated layers is an independentfully functioning photovoltaic cell.

FIG. 6 shows schematically an approach of producing thin-filmmultifunction photovoltaic devices in accordance with the presentinvention. The method includes the following steps: (1) laminatingtogether two or more modules such as the three modules 111, 112 and 113are shown in FIG. 6, which include transparent substrates 601,602 and603, respectively, and, optionally (2) laminating an additionalprotective coating 620 over the whole stack and part of electrical leads630. The last step may be redundant due to existing protective layers inthe laminated modules. Additional bonding or adhesive layers 610 may berequired in the first lamination step to form a bond between the bottomof a substrate of an upper module with the top of the conductive layerof a lower module. Further additional steps in this manufacturingprocess may include making electrical contacts with each exposed cathodeand anode in the stack and providing respective electrical current paths630 to an external circuit.

While the present invention has been described in terms of aphotovoltaic device that is formed from two or more photovoltaic modulesthat are hybridly integrated in a multi-layered stack, the presentinvention encompasses other types of devices as well. That is, inaddition to photovoltaic cells or modules, other types thin-filmelectro-optic modules can be hybridly integrated in a multi-layeredstack. For example, large area light emitting devices (LEDs) can belaminated in a stack of multiple LEDs on top of each other. This couldbe done for different purposes, e.g. to achieve higher brightness,different colors, white-light emitting multi-layered LEDs and others.Furthermore, segmented multi-layered LEDs could be used as displays, inwhich each segment represents a separate pixel. Unlike conventionalpixels, these pixels could produce true color emission across a largearea. Similar to the modules used to form a photovoltaic device, themodules uses to form these other types electro-optic devices include atleast a substrate, two conducting layers, and two or more semiconductorlayers (which form I or more junctions).

Existing lamination techniques can be modified and adopted for use inthe lamination of thin film electro-optic devices such as photovoltaicdevices. FIGS. 7-12 show examples of the lamination processes, whichinclude roll-to-roll lamination of flexible films with rigid substratesand flexible films, multiple film lamination, segmented film lamination,segmented panel-to-panel lamination and others. A variety of laminationmethods could be adopted in manufacturing of thin-film multi-junctionelectro-optic devices. These methods include wet lamination, drylamination, pressure, thermal lamination, hot-melt lamination, chemicallamination, UV-assisted lamination, extrusion lamination andcombinations thereof. Most of these approaches have to be tailored towork with specific thin-film materials and multi-junction designs.

EXAMPLES

FIG. 2 shows an exemplary embodiment of the invention, in which threedifferent photovoltaic modules 111, 112 and 113 are utilized. Maximumsunlight power conversion efficiency of this architecture is about 56%for highly concentrated sunbeam and about 50% for regular sunlightintensity (so called condition AM1.5). All three modules contain activepolycrystalline semiconductor materials based on, for example, a CIGS(Copper Indium Gallium Selenide) material system or a related alloy, andthe corresponding junctions are produced using single-junction designsknown in the art. By varying the In and Ga relative concentrations thebandgaps in layer 111 may be adjusted to about 1.7 eV, in layer 112—toabout 1.4 eV and in layer 113—to about 1.1 eV. The thickness of eachlayer may be in the range of 1 to 5 microns. Each module may alsocontain buffer layers, such as, for example, a thin CdSe layer with athickness in the range of 10 to 1000 nm. The semiconductor layers ineach module may be located between appropriately matched transparentconducting layers 130. The conducting layers 130 may be formed from thinlayers of ITO or ZnO with a thickness in the range of 0.1 to 5 μm. Eachmodule also includes a substrate, such as a polyimide film, with athickness in the range from 10 to 1000 microns, which is transparent inthe appropriate spectral range and which is used primarily as a carrierfor other layers in the module. These modules are laminated so that theyadhere to each other to form a single laminate film with multipleindividual electrical contacts for each module.

The various modules shown in FIG. 2 may be also laminated onto a commoncarrier substrate 210, such as a thin polyimide film with a thickness inthe range of 25 to 1000 microns. This substrate may be coated with metalsuch as Al, Mo, Au or Cu to reflect unabsorbed light back into theindividual modules. As shown, the modules may be staggered or laterallyoffset from one another so that each conducting layer 130 has an exposedregion 230. The exposed regions 230, which may be covered withadditional metallization pattern to provide better conductivity, serveas surfaces that can connect the modules to external electricalcircuits. As a result, the three modules shown in the device of FIG. 2may have up to six electrical output connectors.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that some of the modules include asubstrate made from polyamide.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that some of the modules are inaddition coated on at least one of the surfaces with a thermosettingresin such as ethylene-vinylacetate (EVA).

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that some of the modules are coatedwith a thin protective plastic film, such as polyethylene terephthalate(PET), on the side opposite from the substrate, so as to protectsensitive electronic parts of the module during the lamination process.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that the carrier substrate, such assilicone, is transparent and is attached and laminated on the top of thefirst module 111.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified by laminating additional conductingfilms, foils or wires, so that three of electrical output connectors maybe shorted or connected to the ground without loss of devicefunctionality.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that additional modules havingjunctions with different bandgaps may be laminated and provided withadditional individual electrical contacts. In this embodiment the totalnumber of junctions and bandgaps may be greater than four, and thebandgap values are chosen to maximize device conversion efficiency for agiven number of junctions. Some of the electrical outputs may beinterconnected locally or via an external circuit, so as to produceeither in series connection, in parallel connection, common anode orcommon cathode configurations or combinations thereof.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that the junction layers may beproduced on separate sacrificial substrates and detached from thesesubstrates before or during the lamination process.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that the modules may be bondedtogether to produce a single multi-layered photovoltaic film.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that the modules may be gluedtogether to produce a single multi-layered photovoltaic film.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that the modules are segmented andlaminated onto a single carrier substrate.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that some of the modules arelaminated together so that their substrates are exposed to the lightthat is to be converted.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that the modules that are stackedand hybridly attached to each other are light emitting modules (LEM).Each LEM could be activated and operated independently from the others.Furthermore, each LEM contains an emitting semiconductor layer with adifferent characteristic bandgap and thus different characteristicemission spectrum. Thus, different emission spectra from different LEMscould be combined to produce different color combinations including thatof white light. Also, independent control of emission intensities can beachieved by varying the different currents supplied to different LEMs,which allows one to continuously vary and change the color of thecombined emission of the LEM stack. Furthermore, each LEM may besegmented into an array or a matrix of individual light emitting pixelswith individual electrical controls, so that a stack of segmented LEMswill function as a bright, efficient, true color display.

In yet another embodiment, the apparatus and method described above andshown in FIG. 2 may be modified, so that the modules that are stackedand hybridly attached to each other are electro-optical sensors. Some ofthese sensors may be configured to analyze an optical spectrum. That is,the sensor modules may comprise a stack of layers with multiple quantumdots each having independent electrical output so that they function asa spectrum analyzer of the absorbed light. Other sensors may beconfigured to probe temperature, moisture, impurity content, variousspecific airborne chemicals and other atmospheric conditions.Furthermore, the sensor modules could include micro-fluidic channels andchemical sensors and may be further segmented to be sensitive andresponsive, for example, to specific DNA strands, thus enabling theresulting device to conduct DNA analysis or other types of complexchemical analysis.

FIG. 7 shows an exemplary embodiment of the invention, in which anapparatus and a process are shown for laminating one photovoltaic module702 on a flexible substrate, such as a high temperature polyimide film,onto another photovoltaic module 701 deposited on a rigid substrate,such as soda lime glass. Module 701 may be in the form of a panel, i.e.a flat sheet of rigid or semi-rigid material, the size of which is onthe same order of magnitude as the size of a typical solar cell panel(e.g. 50 cm by 100 cm) and thus may fit entirely onto rollers 710.Several lamination methods could be used including pressure laminationand thermal lamination. A combination of these two methods could beimplemented using a thermosetting adhesive layer of EVA. Module 701 canbe coated with a thin ethylene vinyl acetate (EVA) layer with athickness of about 10-20 microns, after which rollers 710 feed theprepared substrate towards hot rollers 730. Those in turn apply pressure5-10 kg/cm² and heat to achieve local temperatures of about 100° C. atthe modules' contact point, causing the EVA to melt and bond the modulestogether forming a stack 703 that defines a two-module photovoltaicdevice. Generally, relatively thin adhesion layers are necessary forbetter optical transmission between stacked modules, as compared withthe current standard lamination and encapsulation techniques. Roller 720feeds the film with module 702 and maintains the correct tension in thefilm. Module 702 may be laminated either substrate side down orsubstrate side up. In the latter case the substrate of module 702 willalso serve as the top protection layer of the combined module 703.

In yet another embodiment, the apparatus and method described above andshown in FIG. 7 may be modified by including an aligner 740, so that thelaminated module 702 may be aligned, laterally offset and attached tothe module 701 to thereby expose electrical contacts on both modules forsubsequent connections to external electrical circuits. Currentlamination techniques generally do not provide such alignmentcapabilities and precision positioning in the attachment process, andtherefore are mostly useful for encapsulation. Furthermore, additionalmonitors, sensors and gauges 750 may be used to monitor and reportprocessing parameters, such as pressure, temperature and humidity, aswell as module conditions, such as feeding speed, film tension,attachment failures and others.

In yet another embodiment, the apparatus and method described above andshown in FIG. 7 may be modified, so that the laminated modules 701 and702 have metal grids on at least one of their conducting layers in orderto reduce contacts ohmic resistance. These metal grids may have matchingpatterns. Furthermore, aligner system 740 may then be also used to alignthe two metal grids exactly on top of each other, in order to avoidcross-shadowing, in which the light shadow from the upper metal grid isnot overlapping with the light shadow from the lower grid.

In yet another embodiment, the apparatus and method described above andshown in FIG. 7 may be modified, so that the laminated module 702 is amulti-junction laminate film consisting of at least two differentlaminated photovoltaic modules.

FIG. 8 shows an exemplary embodiment of this invention, in which anapparatus and a process are shown for laminating a module 802 having aflexible substrate onto another module 701 having a rigid substrate. Asacrificial flexible carrier substrate 804 is used in this case tofacilitate the lamination process and reduce the overall thickness of aresulting multi-junction device. Carrier substrate 804 may be laminatedto module 802 in advance using, for example, cold lamination with apressure sensitive adhesive to produce a composite film 805. Module 802may pealed off and separated from the carrier 804 using rollers 820 and825. This approach allows one to use a thinner flexible substrate inmodule 802, thus reducing the overall thickness of the resulting device803 to thereby improve light transmission between the modules.

FIG. 9 shows an exemplary embodiment of the invention, in which anapparatus and a process are shown for laminating two (or more) modules910 and 920 having flexible substrates onto another module 901 having arigid substrate, to produce sequentially laminated stacks provided bylaminating units 902 and 903, respectively.

FIG. 10 shows an exemplary embodiment of the invention, in which anapparatus and a process are shown for laminating together two modules1001 and 1002, which both have flexible substrates. Although differentlamination methods could be used, including pressure lamination, thermallamination and others, extrusion lamination may be particularlyadaptable for this process, in which a thin layer of melted adhesive1003 is applied between the modules, followed by cooling and rollinginto a roll 1004.

FIG. 11 shows an exemplary embodiment of the invention, in which anapparatus and a process are shown for laminating a segmentedelectro-optic module 1102 onto another segmented electro-optic module1101 to form a segmented electro-optic laminate 1103. Segmentedelectro-optic module 1102 includes a flexible substrate and segmentedelectro-optic module 1102 includes a rigid substrate. A sacrificialflexible carrier film 1104 may be used in this process. Furthermore,each segment of the modules 1101 and 1102 may represent a previouslytested, good known part. Laminating rollers 1110 and aligner 1120 areused to align and attach the respective segments of modules 1101 and1102 to one another as monitored and controlled via a view-vision system1140. The lamination rollers 1110 also serve to peal off the sacrificialsubstrate 1104.

FIG. 12 shows an exemplary embodiment of the invention, in which anapparatus and a process are shown for laminating a segmentedelectro-optic module of an individual panel 1201 onto another segmentedelectro-optic module of an individual panel 1202. Each segment of theprocessed modules may represent a good known part. Individual panels maybe made from either rigid or flexible substrates to satisfy theaforementioned multi-layer electro-optic hybrid integrationrequirements. In this embodiment, pick-and-place robotic tools 1210 maybe used to facilitate high volume production and minimize manufacturingcosts. Also, vacuum lamination apparatus 1211 and processes can beutilized to further improve the performance and reliability of theresulting multi-layer device 1203.

Variations of the apparatus and method described above are possiblewithout departing from the scope of the invention.

1. A method of producing a hybrid multi-junction photovoltaic device,comprising the steps of: providing a plurality of planar photovoltaicsemi-transparent modules, each of the modules being a fully functional,thin-film, photovoltaic device and including first and second conductivelayers and at least first and second semiconductor layers disposedbetween said conductive layers, said first and second semiconductorlayers defining a junction at an interface therebetween; disposing themodules one on top of another and hybridly adhering them to each other,wherein at least one of the modules is configured to convert a firstspectral portion of optical energy into an electrical voltage andtransmit a second spectral portion of optical energy to another of thejunctions that is configured to convert at least part of the secondspectral portion of optical energy into an electrical voltage.
 2. Themethod of claim 1, wherein said step of adhering is achieved bysequentially laminating each of the modules to another of the modules.3. The method of claim 1 wherein the disposing step includes laterallyoffsetting the modules from one another.
 4. The method of claim 1further comprising disposing transparent insulating layers between saidmodules.
 5. The method of claim 1 further comprising exposing a part ofsaid conducting layers of every module so that they are accessible forconnection to external electrical circuits.
 6. The method of claim 1wherein providing said plurality of modules includes deposition of CIGSbased absorber layers.
 7. The method of claim 1 wherein providing saidplurality of modules includes deposition of semiconductor absorberlayers with different bandgaps optimized for enhanced power conversionefficiency.
 8. A method of producing a hybrid electro-optic devicecomprising steps of: providing a plurality of planar electro-opticsemi-transparent modules, each of the modules being fully functional,thin-film, electro-optic device and including first and secondconductive layers and at least first and second semiconductor layersdisposed between said conductive layers, said first and secondsemiconductor layers defining a junction at an interface therebetween;disposing the modules one on top of another and hybridly adhering themto each other; applying an electrical contact to the conducting layersof each of the modules.
 9. The method of claim 8 wherein said steps ofproviding said plurality of electro-optic modules further includessegmenting said modules into a plurality of segments.
 10. The method ofclaim 9 further comprising aligning said segmented modules with respectto one another and providing electrical connectivity for said segments.11. An apparatus for hybrid manufacturing of a multi-layeredelectro-optic device comprising: a roll-to-roll system for feeding aplurality of electro-optic modules, at least one of them being on aflexible substrate, each one being fully functional, thin-filmelectro-optic device, including first and second conductive layers andat least first and second semiconductor layers disposed between saidconductive layers, said first and second semiconductor layers defining ajunction at an interface therebetween; an arrangement for monitoring andmaintaining speed, tension and temperature of the modules as theytraverse the roll-to-roll system; at least one pressure roller to exerta compression force for attaching two of said modules on top of eachother in a continuous fashion; and an aligner system for positioning andlaterally offsetting one of the modules over another of the modules. 12.The apparatus of claim 5 wherein each module comprises a plurality ofsegmented modules and further comprising a view-vision system forselecting good known module segments, separating and detaching themodule segments from a carrier film, and removing remaining unusedmodule segments.
 13. An apparatus for hybrid manufacturing of amulti-layered electro-optic device comprising: a pick and place systemfor handling a plurality of electro-optic modules, each one being fullyfunctional, thin-film electro-optic device, including first and secondconductive layers and at least first and second semiconductor layersdisposed between said conductive layers, said first and secondsemiconductor layers defining a junction at an interface therebetween;at least one pressure member to exert a compression force for attachingtwo of said modules on top of each other in an automated fashion; and analigner system for positioning and laterally offsetting one of themodules over another of the modules.
 14. The apparatus of claim 7wherein each module comprises a plurality of segmented modules andfurther comprising a view-vision system for assisting an alignmentprocess between segments of different modules.
 15. A process formanufacturing a hybrid electro-optic device comprising: feeding aplurality of electro-optic modules through a roll-to-roll system, atleast one of the modules having a flexible substrate, each of themodules being a fully functional, thin-film electro-optic device, eachof the modules including first and second conductive layers and at leastfirst and second semiconductor layers disposed between said conductivelayers, said first and second semiconductor layers defining a junctionat an interface therebetween; positioning and aligning one of themodules over another of the modules; monitoring and maintaining speed,tension and temperature of said modules while being fed through theroll-to-roll system; exerting a compression force for attaching two ofsaid modules on top each other.
 16. The process of claim 15 furthercomprising a deposition of adhesive layers on at least one side of eachof said modules.
 17. The process of claim 15 further comprisinglaminating said modules on top of each other.
 18. The process of claim15 further comprising attaching a sacrificial flexible carrier to atleast one of said modules.
 19. The process of claim 15 furthercomprising exposing a portion of said conducting layers of each moduleand providing an electrical connection from each of the conductinglayers to an external circuit.
 20. The process of claim 15 wherein saidmodules are configured as panels and further comprising aligning andattaching said module panels on top of each other.